This invention refers to an integrated process for repairing by welding of machines or machine components made of metallic material of any chemical compositions and difficult to be welded, damaged by cracks or fissures because of fatigue or overload and squash or excessive wear using the correct combination of machanic, thermic and metallurgic actions, in order to eliminate or minimize internal stresses accumulated during the machine or component operational life, remove and repair the failure-crack, fissure, or squash--and guarantee a minimum residual stresses after repair, being the machine or component in an original technical condition, as far as strength and mechanical-metallurgic integrity are concerned.
Until this invention, the loss was complete in respect to the failure due to squash or excessive wearing in machines or components, made of metallic material difficult to be welded, because of high sensitivity to thermo-mechanic stresses and easy transformation into more energetic metallurgic phases susceptibility to the formation of cracks-inducted in a process of localized heating, when such elements are, also a characterized by complex forms and favourable to additional loads such as of the type of mechanic restriction or high variation in section modules. The whole machine or component had to be replaced. In such a situation, besides this total loss, the long and expensive time the machine remains stopped for repairs must be computed.
Up to now, the repair of elements which had problems in simple or more complex constructive situations covered by this patent followed the method of welding preceeded by pre-heating, based on the control of the temperature of the base metal, and a heat treatment for stress relief after the weld. In such conditions, the well-known procedures of heat weld have been adopted, in ovens as well as in determined sections or elements by means of electric resistances applied on the spot and covered by thermic insulating material, like a wrap. The rod to weld, or the deposit material, has been identified as being the more adequate for the base metal, taking into consideration the strength it must give to the base metal.
Besides the incidence of induced distortion in the repaired machine or machine component, it was also observed that the processes adopted up to now always accuse failures, mainly failures due to ruptures, in the repaired spot as well as in the rest, more commonly produced by effects of structural stresses induced by mechanisms of mechanic restriction, due to distortion or even residual stresses developed in elements of high variation of section modules, or inadequate deposit. These effects have greatly prejudiced such repairs.